FCKEditor does not appear on Joomla admin page

Description

Hi!

I'm using a PC with Windows XP SP2/Firefox 2.0.0.7. We are running a server with SuseLinux10.2/PHP5/mySQL5 and using the Joomla CMS with FCKEditor mambot v2.4.3.
We realized that on the admin pages of Joomla (backend) FCKEditor doesn't appear since Firefox latest update. (I tried again, it works on 2.0.0.6 and doesn't on 2.0.0.7).
FCKEditor works on the front-end side, but doesn't work on the back-end.
I attached the screenshot showing the errors.

It resides on an internet domain's DMZ on the web server (Apache2) what
is behind a firewall (so it has local IP address). It contains all the
FILE components of Joomla CMS (including FCKeditor). But the DATABASE
server is different (where the Joomla database can also be found) but
resides in the same subnet. And naturally it can be reached from
anywhere on the internet.
(On the ticket description I forgot to mention that we use Joomla 1.0.12.)

I mean, this problem is most likely to happen if the page take holds FCKeditor runs in a domain different from FCKeditor. So, if the app is running at bpa.hu, but FCKeditor is coming from, for example, static.bpa.hu, then you may have problems. Can you confirm this situation?

All the application (incl. FCKed.) resides on the same server and the same domain, and as I mentioned FCKEditor works well if I call it on the front side of the CMS (wich sits on that same web server and also the same domain).

Well, we are not able to replicate it here without running Joomla. To work on it at our side, we should be pointed to a sample page were we can see the error, or even have a TC for it. Otherwise this issue must be handled at the mambot side, which would work to provide us the TC.